The visual competence of the pigeon appears to be comparable to our own, in that 'people', 'trees', 'pigeons', etc, are readily identified in naturalistic color slides. The author proposes, however, that the correspondence in visual categories between people and pigeons actually masks fundamentally different modes of visual comprehension. It is shown that the genetic and perspective transformations which generate natural classes of images may be expressed (to a certain tolerance) as a series of constraints on "allowable" permutations of sets of local features. We accept the resulting images in consideration of those constraints. The author argues that the pigeon, in contrast, is unaware of the constraints, and so is willing to accept any permutation of the feature set, however far the deviation from a natural image. Research is both reported and proposed, which demonstrates that the pigeon is sensitive to the local features, but not to the higher-order features, of classes of images.